foo.jar:
% content bar %child/
% content foo %
  foo.js
* foo.css
  bar.js          (subdir/bar.js)
  qux.js          (subdir/bar.js)
* child/hoge.js   (bar.js)
* child/baz.jsm

% override   chrome://foo/bar.svg#hello   chrome://bar/bar.svg#hello
